Method of making beta lactose



Dec. 5, 1939. P. F. SHARP El AL 2,182,618

METHOD OF MAKING BETA LACTOSE 2 Filed July 24, 195'? INVENTORS Fau/ FrancwJiza/p BY awdfiirrwyfland 7 7 1 ATTORNEY.

usual sense.

Patented Dec. 5, 1939 UNITED STATES PATENT OFFICE 2.182.618 rm'rnon or MAKING BETA LAOTOSE Paul Francis Sharp and David Birney Hand, Ithaca, N. Y., assignors to Cornell Research Foundation, Inc., Ithaca, N. Y., a corporation of New York Application July 24, 1937, Serial No. 155,47

60laims.

process generally in use. As distinguished from this, we discovered a direct or dry process, in which the materials remained in a substantially dry or pulverulent condition during the conversion to beta lactose,the fundamental discovery 1 being that the water normally present in the dry materials was, under certain conditions, sufllcient to permit the conversion into beta lactose. The

present invention is an improvement relating to said dry process, by which the range of materials it may use is extended and its action facilitated by the use of supplemental water. This water is limited to such additional amounts as will not destroy the essentially dry or pulverulent condition of the materials present, so that the mass does not become viscous or doughy, or wet in the The present improvement therefore retains the advantages of our fundamental dry process, while permitting a flexibility of application to various forms of manufacturing, including the use of various forms of lactose which are deficient in water content. Various other objects and advantages will become apparent as the description proceeds.

In the drawing forming part of this specification there is shown one illustrative form of apparatus by which the process may be carried out, consisting for example of an autoclave comprising a container l surrounded by a jacket 2 and closed by a cover 3, the whole being mounted or suspended on lugs 4. A pipe 5 is provided to introduce steam or other heating medium into the jacket 2 so as to heat the container l, and a second valved pipe 6 permits the steam or other heating fluid to pass through. A drain plug 1 is provided for the jacket 2, and a drain plug 8 is provided for the container I. The cover 3 also has an aperture III, which can be closed by the supplementary cover II. A stirrer I2 is mounted on the shaft l4 and is driven through the gearing l5 by any suitable means such as the belt pulleys l6. The'interior oi the container I is tapped by a pipe line I! connected to a small boiler or vaporizer l8, in which steam may be generated. A valve I9 is provided in the pipe IT to control the steam. A pipe 20 is also provided for the exhaust, which may be either to the open air or to a vacuum if lower pressures are desired, and this pipe 20 is provided with a control valve 2|. A gauge 22, preferably of the combined pressurevacuum type, is also provided, and the temperature can be read by an ordinary thermometer. The reference numeral 25 indicates the lactose being treated, as will be described.

While the present invention comes in general under the head of the dry process previously 10 mentioned, inasmuch as the water of crystallizat on or other water driven off from the substantially dry materials may be-largelyresponsible for their conversion into beta lactose, the present invention is more flexible in its application and can operate successfully on a wider range of materials, due to the fact that controlled amounts of steam or water may be added as well as subtracted to the lactose materials under treatment,

while they are heated and agitated, without losing their pulverulent character. The present invention is accordingly not restricted to the conversion into beta lactose of alpha lactose hydrate (the ordinary milk sugar of commerce),

but has also been applied successfully to other forms of lactose such as dehydrated alpha lactose, or to mixtures, as for example the mixture of alpha and beta lactose which is obtained as a result of drying a lactose solution by the methods used for drying milk. It is possible to utilize non-crystalline forms of lactose, such as spray dried or roll dried lactose.

If the lactose or mixture of lactoses whichit is desired to convert into the beta form does not contain sumcient water for the conversion, it is necessary to incorporate a small amount of water with the lactose. The amount of water which it is necessary to incorporate is generally less than 5 per cent. of the weight of lactose in the autoclave. The minimum amount of additional .moisture required 'will vary with the moisture content of the lactose. We have found that this incorporation of a small amount of water can be accomplished satisfactorily, and such products converted into substantially pure beta. lactose without losing their pulverulent character, by introducing small amounts of supplemental water in the form of steam or water vapor, preferably although not necessarily after the agitated lactose has attained a temperature above 100 C.

Referring now to the drawing, which illustrates by way of example one way of controlling the amount of water introduced in carrying out the process,the lactose material or materials 25 in their pulverulent form are heated in the container I to preferably in the neighborhood of to C. and agitated. The required amount of water is slowly vaporized in the auxiliary vessel or boiler l8, from which the steam passes through the valve I9 and pipe l1 into the container I. Sufficient water or water vapor must be present in the autoclave or in the atmosphere to cause the transformation to beta lactose, but the water or water vapor should not be present in such large amounts as to allow solution to accumulate to the extent that the material becomes stifi or doughy, or loses, except perhaps locally or temporarily, its pulverulent character.

As the lactose under treatment is thus heated and agitated, any water of crystallization or other water present in the pulverulent materials is driven off, and being intimately associated with the particles some of this water, with some of the supplemental vapor introduced as described, condenses on the surface of the particles to form on them minute, highly concentrated lactose solutions, in which equilibrium between the forms of lactose in the solution is soon attained. At this high temperature beta lactose is the least soluble of the forms of lactose present in the solution and consequently crystallizes out. This again sets free the small amount of water present, which then serves to form more such solutions, and the process is repeated and continues until substantially all, or as much as desired, of the lactose materials is transformed into beta lactose. This transformation usually requires from thirty minutes to an hour. When it is sufficiently completed the valve 2| is opened, with the valve I9 closed, and the water or steam is allowed to slowly escape. The autoclave is then opened and the dry beta lactose is removed. Due to the fact that any moisture added was so .limited that the materials retained their pulverulent condition, and were continuously agitated, there is generally very little caking, and the resulting product is in the form of powdered beta lactose in the crystalline form.

The operating conditions are subject to various modifications without departing from this invention. For example, the time for complete conversion depends upon the relation of the charge of lactose materials used to the capacity of the apparatus, and the nature and size of any crystals, the vapor present, and the temperature, rate of heating and agitation. Some of the water vapor may be permitted to escape during the heating, but if too much water is allowed to escape early in the heating process complete conversion to beta lactose will not occur, or the -time for conversion may be unduly prolonged.

The transition point between alpha and beta lactose, as generally referred to in chemical literature of lactose, lies at approximately 93 C., but it is now known that it varies over a wide range. We have given temperature and time conditions in one example of conversion of ordinary milk sugar of commerce (alpha lactose hydrate). Other conditions of time and temperature can be used without departing from the invention, but if lower temperatures approaching the conversion temperature are used the time of conversion will be unduly prolonged, and if higher temperatures are used the product may be less desirable as a result of browning.

In order to minimize still further any slight tendency to browning, care may be taken to evacuate the air in the container I after it is first filled and sealed. This may be done by applying a vacuum to the exhaust pipe 20, or by blowing out the air by steam from the pipe II, or by merely leaving the valve 2| open when the contents of the container I is being heated, so that the expansion of the air and the steam from the lactose forces most of the air out. If a vacuum pump is used, it should not be left on for too long a period, particularly at the higher temperatures; otherwise the water present may not be suflicient to permit the desired conversion into beta lactose, or the conversion may be unduly prolonged.

While it is generally desirable to convert as large a proportion of lactose into the beta form as possible, any smaller proportion may be obtained with our invention by discontinuing the process at an intermediate stage or by restricting the moisture content or temperatures,'and any such partial or incomplete operation will be understood as falling within the scope of the present invention when such beta lactose as is produced results from the process herein de-- scribed and claimed.

While we have in the foregoing described a certain specific example, it will be understood that it is for the purpose of illustration to make clear the principles of the invention, which is not limited to the particular form shown, but is susceptible to various modifications and adaptations in different installations, as will be apparent to those skilled in the art, without departing from the scope of the invention as stated in the following claims.

We claim:

1. The process of producing beta lactose which consists in heating any other form of lactose while in a pulverulent condition in an atmosphere of water vapor at a temperature maintained above the transition point and vapor pressure sufiiciently high to cause the formation of a temporary solution on the surface of the lactose particles, while limiting the amount of moisture so that the particles remain in a pulverulent condition, continuing said process until the lactose is converted into the beta form, and then permitting the surplus moisture to escape, leaving dry crystalline beta lactose.

2. The process of producing beta lactose which consists in heating any other form of lactose while in a pulverulent condition in an atmosphere of water vapor at a temperature maintained above the transition point and vapor pressure suificiently high to cause the formation of a temporary solution on the surface of the lactose particles, while agitating the same and limiting the amount of moisture so that the particles remain in a pulverulent condition, continuing said process until the lactose is converted into the beta form, and then permitting the surplus moisture to escape, leaving dry crystalline beta lactose.

3. The process of producing beta lactose which consists in heating any other form of lactose while in a pulverulent condition, supplying a limited amount of moisture in a restricted zone moisture from an exterior source to assist conversion, said supplemental moisture being so limited as to permit the particles to remain in a pulverulent condition, whereby the alpha lactose hydrate crystals are transformed into beta lactose crystals without becoming a viscous mass.

5. The process of producing beta lactose which consists in heating and agitating alpha lactose hydrate crystals at a temperature maintained above the transition point, supplying them with supplemental moisture from an exterior source to assist in conversion, said supplemental moisture being so limited as to permit the particles to remain in a pulverulent condition, and permitting the moisture to escape after it has assisted in the conversion, whereby alpha lactose hydrate crystals are transformed into dry beta lactose crystals without becoming a viscous mass. 6. The process of producing beta lactose which consists in heating at a temperature maintained above the transition point and agitating any other form of lactose while in a pulverulent condition, supply ng supplemental moisture from an exterior source to assist in conversion, said supplemental moisture being so limited as to permit the particles to remain in a pulverulent condition without becoming doughy or viscous, and permitting the moisture to escape after it has assisted in the conversion, whereby the lactose is converted into dry crystalline beta lactose.

PAUL FRANCIS SHARP. DAVID BIRNEY HAND. 

